Have you ever got home from a terrible day of lectures, labs, or library revision and decided to get some ice cream on sale and eat far too much of the tub as a treat? Of course, you have, and who could blame anyone for indulging in some late-night snacking? Unfortunately, your body will.

New research into circadian rhythms has been looking at the links between late night snacking and obesity. Whilst it’s easy to just blame the late-night snacking itself, Jonathan Cedernaes and his team of researchers at Uppsala University are the latest group contributing research that suggests the lack of sleep itself causes us to pile on the pounds due to changes in our metabolism. Cedernaes has conducted previous research indicating sleep deprivation makes us want to eat higher calorie food.

Who could blame anyone for indulging in some late night snacking? Unfortunately, your body will

Cedernaes is keen to tell everyone that “sleep is not just to conserve energy, it has so many functions” and this study looks at how it changes metabolism, specifically muscle and fat mass. 15 volunteers had two testing sessions where they gave muscle and fat tissue samples; one testing session where they had over eight hours of sleep and the other with no sleep. Comparisons between the tissues yielded interesting results.

Sleep deprivation was shown to make cells more likely to absorb lipids and thereby increase fat tissue in the body. It also lowered muscle mass by reducing structural protein levels, preventing the construction of muscle mass. Whilst diet and exercise can counteract such changes, lack of sleep makes maintaining this muscle mass harder. The study also found that lack of sleep increases inflammation in the body, increasing the chances of type 2 diabetes.

Sleep deprivation was shown to make cells more likely to absorb lipids and thereby increase fat tissue in the body

This was driven by epigenetic changes to the DNA. Small chemical groups on the DNA molecule (such as methyl groups) act as ‘on/off switches’ that changes the expression of the genes. Epigenetic modifications are a blueprint for this expression and are considered to create a ‘metabolic memory’ that regulates a person’s metabolism. Cedernaes found that DNA methylation changed. Cedernaes notes that the epigenetic changes in the fat tissue samples, there were similar DNA methylation levels to people with obesity and type 2 diabetes.

The study only focuses on short-term changes in a small group of people, and the authors have said that further research is necessary to investigate this phenomenon for people with sustained sleep deprivation or for people working constantly changing shifts.

Epigenetic modifications are a blueprint for this expression and are considered to create a ‘metabolic memory’ that regulates a person’s metabolism

There is a concern for the health of people forced to work long shifts where hours are constantly changed due to the combined circadian stresses and a decrease in exercise and diet quality. 700 million people are estimated to work in a shift pattern, and that trend is increasing. In Britain, regular night shift workers went up by 260,000 people.

A meta-analysis of 28 studies looking at night shift found a 29% increase in the probability of obesity in night shift workers, and research done by Cedernaes and other circadian research can help us better understand how this works.